September 09, 2012

IE-speaking West Europeans are West Asian-admixed relative to Non-IE speaking Basques

Previous ADMIXTURE experiments have shown that the Basques differ from the Indo-European speaking Europeans primarily due to a lack of a "West Asian" genetic component most strongly represented on the highlands of West Asia, from Anatolia and the Caucasus through Iran to Baluchistan. The same component is "missing" from ancient European DNA prior to 5kya, making it a good candidate for an element present in the elusive Proto-Indo-Europeans.

I wanted to test the admixture of IE-speaking populations formally, so I used threepop as implemented in TreeMix which performs a formal f3 test of admixture. According to Patterson et al. (2012):

An important feature of this test is that it definitively shows that the history of mixture occurred in population C; a complex history for A or B cannot produce negative F3(C; A,B).

A negative Z-score of the f3 test is unambiguous evidence of admixture, but a zero or positive one does not exclude it.

I report f3 statistics of the following form:

f3(A; B, West_Asian)

where West_Asian consists of 50 random individuals drawn from the K7b West_Asian component.

The full list of populations used in this experiment can be seen below. They include two sources of Basques (from the HGDP and 1000Genomes Project, from France and Spain), as well as 22 Indo-European speaking populations from Western Europe

I set A as each of the 24 populations, and calculate f3-statistics of the form f3(A; B, West_Asian) where B is any one of the remaining 23 populations. Thus, there are 24*23 = 552 f3-statistics in total, of which 2*22 = 44 are of the form f3(IE; non-IE, West_Asian).

the remaining f3(IE1; IE2, West_Asian) statistics to be either negative or not, depending on different levels of West_Asian-related admixture in different IE populations associated with either the Indo-Europeans or other, later, population movements emanating from West Asia.

My expectation is confirmed by the evidence. You can see all f3 statistics in the spreadsheet. I note that:

(1) Here is a histogram of the 44 f3(IE; non-IE, West_Asian) comparisons:

42 of 44 Z-scores are negative and significant, suggesting that most IE-speaking West European populations are West Asian-admixed relative to non-IE Basques. The two that are not, involve A='Orkney_1KG', which is a drifted island population. According to Patterson et al. (2012):

As mentioned earlier, the only case where the f3-statistic for a population that is truly admixed fails to be negative is when the population has experienced a high degree of population-specific genetic drift after the admixture occurred.

(2) All f3(non-IE; IE, West_Asian) statistics are positive. With the caveat about drift in mind, there does not seem to be any evidence that Basques are more West Asian-admixed than any other population.

(3) Here is a histogram of the 462 f3(IE1; IE2, West_Asian) statistics:

This shows evidence in differences in West_Asian admixture in some but not other IE populations. 55 of the 462 comparisons show significant evidence of admixture. These mostly involve German, French, and Italian populations vs. Iberian and British Isles ones. As mentioned above, this may reflect either the diminution of Indo-European-related West Asian ancestry across Europe, or it may be due to post-IE population movements.

Discussion
It is becoming increasingly apparent that modern Europeans are the descendants of both early Neolithic farmers, presumably from the Levant or Anatolia, as well as the indigenous Mesolithic hunter-gatherers. Neolithic ancestry has persisted most strongly in southern Europe, and in Sardinia above all. Mesolithic ancestry has persisted most strongly in northern Europe, and especially in the Baltic area; however, it is everywhere in the minority, as evidenced by the ~10-fold diminution of mtDNA haplogroup U related lineages from near 100% in the earliest samples until today.

In all probability there do not exist unmixed descendants of either early Neolithic or Mesolithic Euroeans. Intriguingly, one population that may be most strongly descended from the Mesolithic Europeans are the Saami, who possess very high levels of mtDNA haplogroup U5b. But even in their case, there is evidence of more recent influences, such as Y-haplogroup N1c.

The Saami have always been somewhat of a puzzle for prehistorians, with some attributing their physical appearance to survival of cold-adapted Paleolithic northern Europeans, while others attributing it to more recent movements from Siberia. As it is so often the case, both may have been partially right: it is now revealed that the Saami are not unique in possessing affinities with northeast Asians and Amerindians, so they are descended both from the Mesolithic northern European substratum (as evidenced by mtDNA haplogroup U5b) and from more recent Siberian peoples, and are thus positioned betweeneast and west for more than one reason.

In the rest of Europe things were not any simpler. Both analysis of modern populations, as well as the mounting ancient DNA evidence ought to have convinced us by now that "there's something about Sardinians." It does seem to appear that this island population represents has preserved most faithfully the early Neolithic European gene pool, which, as it turns out, took its time mixing with the indigenous Mesolithic populations, since it is still evident down to the Iron Age. But, all things come to an end, and so did the domination of ancient Europe by Sardinian-like people.

In continental, and especially, northern Europe, the Neolithic inhabitants, resembling modern southern Europeans, eventually admixed with the Mesolithic foragers. A legacy of this event, as well as, possibly further incursions from the east, combined to give modern northern Europeans a greater affiliation with the east of Eurasia. But, it turns out, things were not much simpler in southern and western Europe.

The modern Basques share the East Eurasian-like admixture of continental Europeans, albeit to a smaller degree than people living in the north. They, like other Europeans are a mix of Mesolithic and Neolithic peoples. But, one thing stands out in their case: their language is not Indo-European and they live surrounded by Romance Indo-European speakers. In older times, their neighbors were Indo-European Celts, some of which have survived in places like Ireland. Further away, live Germanic peoples, some of which ventured into Iberia, without much affecting the local population. One thing is certain: the Basques can no longer be seen as unmixed descendants of Cro-Magnon man. But, if they have not continued as living fossils of Paleolithic man, then, what is to account for their linguistic peculiarity?

In the current post I make one such suggestion in the framework of my theory on the Indo-Europeanization of Europe. I showed that Basques differ from all their Romance, Celtic, and Germanic fellow West Europeans in lacking a "West_Asian" influence. I have previously investigated segments of such influence in two northern Europeans. In the future, with new instruments, such as ADMIXTOOLS, we may be able to figure out exactly when other European populations were affected by this influence. For peoples living close to West Asia (e.g., Greeks or Italians), the pattern may be obscured by recent historical contacts. But, the same will probably not be true for populations living in far Western Europe (e.g., Iberians or Irish).

If my theory is correct, then this signal will postdate the 5kya mark. By how much? It is not clear how long the Indo-Europeans of western Europe maintained themselves separately, perhaps as I have speculated, as a trading/military elite centered around metallurgy and its products. Ancient DNA research has the potential of resolving this issue by first identifying the earliest arrival of the West Asian influence, and, subsequently, detecting the first emergence of something akin to the modern population. One way or another, the cat is out of the bag, and in a the coming years many of these issues will be resolved.

19 comments:

"IE-speaking West Europeans are West Asian-admixed relative to Non-IE speaking Basques"

I really don't think you can talk about components like that when they are so closely related.

It's all good to talk about west eurasian and east eurasian components and how they merged when two different peoples mixed but that's not the sane when talking about similar west eurasian components. All you have to do is make a little tweak and you end up getting different distributions of components. Basically, because the components are so close, they interchange with parts of each other, making it obvious that each component does not represent a people.

Dienekes, Is this another way of depicting the results contained in your K7b spreadsheet that you referenced and linked? I note that the spreadsheet shows between 9 and 10% West Asian for Irish, Cornwall,English and "Orcadian" and shows 0% for French Basque (there were no Spanish Basques listed unless I missed it).

Also, regarding the supposed uniqueness of Sardinia, wasn't there considerable infusion of Greeks, Phoenicians and Romans, or did they not leave a trace?

I ask myself how all this fits in with the mass graves associated with cultural aspects of the LBK culture like the Herxheim site or the Talheim Death Pit. It makes me wonder what situation was present when other population elements moved into Europe and did they dislike what they saw? Or was it already a dying land?

<< My guess is that the Caucasus component is from the scattered Northern Tribes of Israel, and it would have begun being introduced around 2700 years before present. >>

Do you have any evidence for that?

The mythical lost tribes would have been a tiny percentage of the population of West Asia and there is no reason to associate the Hebrews with either the spread of Indo-European or metal age technology. Moreover the Hebrews are associated with Semitic languages and Afro-Asiatic genes, both of which are absent in Europe. The Caucasus component bespeaks the introduction of a racially distinct component that entered Europe from the Anatolian and Caucasus region not an ethnic group that had wandered around the south for centuries mixing with other components.

Contra Aaron, I think the Caucasian is the older component, coming in from Anatolia directly with people speaking Hittite family languages (~5K-3K BC) who were then supplanted in Europe by a later, circum-Caspian migration that brought in the Gedrosian genes with a mostly North Euro population (starting around 2000BC).

The evidence for my theory that the Caucasus component comes from the 10 tribes is entirely circumstantial, but as far as I am aware, there is no data that would contradict such a theory, so I figure it should at least be suggested. I gladly await further data that will disprove my theory.

If you look at the groups from the Jewish Diaspora and compare them to their neighbors, you can see that they have an increased level of Caucasus component.

Iranian-40.3Iranian Jews-49.3

Moroccan-6.7Moroccan Jews-34

Yemenese-27.7Yemenese Jews-33.9

Additionally other groups such as the Samaritans (48.8) and Druze (49.5) have high levels of the Caucasus component.

So we would expect that the scattered tribes would likewise carry a high level of Caucuses component.

When they were deported they were mixed with the Assyrians so they would loose their identity as a people, during this mixing they most probably began speaking an IE language rather than a Semitic one.

The fusion of two cultures created an environment of shared ideas which inevitably led to increased technology, not to mention access to chariots.

They quickly spread through Europe and mixed with everyone along the way as they expanded, Indo European dialects quickly became the prominent languages because they were the people in power.

It will be interesting to see the genomes of Celtic, Germanic, Dacian and Thracian peoples to see if their genomes were Caucuses shifted relative to modern humans as they could be possible carriers of this Caucasus component into Europe.

Circum-Caspian migration as the source of West Europen Gedrosian is less than unlikely. Just imagine a map and place the frequency of this component in Europe. There is a North Atlantic (British Isles + adjacent coastal) maximum and decreasing into the East, included a "wall" in the East that contains virtually zero Gedrosia, included countries next to the Black Sea. A relatively recent East to West Continental migration as a source of this distribution seems to be rather unlikely to me.

"When they were deported they were mixed with the Assyrians so they would loose their identity as a people, during this mixing they most probably began speaking an IE language rather than a Semitic one."

So they mixed with the Semitic Assyrians and and picked up IE language during this mixing. Quite interesting theory...

A lot of folks have elevated Caucasus components compared to most of Europe.

Also documented IE already existed all the way in Europe by that time (2700 BP).

You should stop try and explanin the whole history from the Bible. Those tribes were not that important.

Aaron, you seem to concede that your fantasy has absolutely no evidence. Moreover it appears to be nonsense contrary to known linguistic facts. Ascience is no help to science, it is its opposite. Science is in part precisely the endeavour to get beyond fanciful and grand ethnocentric myth.

There is no historical evidence for the existence of 10 lost tribes. Likely the story was invented to give the Hebrews, a small wandering homeless tribe, some sense of self-importance, that they were a great nation and would be in the future. Their literature is centered around a genocidal god who would destroy their neighbours, increase their numbers and deliver the earth to them. Also the myth of the lost tribes would have served as a warning to the Hebrews not to apostacise from the jealous God: they would disappear into nothingness if they rebelled against him. The Hebrews might be characterised as a small, powerless, paranoid religious sect seething with resentment and aggression toward their more successful neighbours and the mythological 'history' served to express, reinforce and glorify their peculiar ethnic character and to provide some sort of group survival stategy. But there is certainly no scientific reason to atttribute Indo-European civilization and the spread of metallurgy to the "lost tribes".

The presence of West Asian/Caucasus is circumstantial and pre-dates the identity of Hebrew people who probably would have scored a subset of predominantly Atlantic-Med, Caucasus/West Asian, and SW Asian ancestry - not necessarily in that order. Minor components of N.Euro which and N.African were probably present as well.

I have never heard anyone say that the ten tribes simply never existed.

If your argument is that they simply did not contribute significantly to our current gene pool, we may be able to have a discussion, but to say that their existence and deportation by Assyria never happened seems far-stretched.

When Assyria deported the tribes, they were sent to many different areas of the North, so I don't see why they could not have adopted a IE language.

Israel was highly advanced for the time and the Northern Tribes represented a non-negligible fraction of the worlds population, to simply say that an entire population did not reproduce seems illogical and I see no reason why traces of their DNA may not be present today.

I know very little about the spread of metallurgy, but I do find it interesting that the most prized weapons were made of "Damascus" steel which is the capitol of the Northern Tribes, even though the ore for the steel came from India.

Also, people assume the need for signs of Hebrew culture among the lost tribes, but I see no need. They were an apostate group that worshiped idols and already had a strong affinity for the groups they mixed with in the North since they were already worshiping their idols.

Plus, I'm not trying to prove anything from the Bible. I did not say we are all descended from 2 individuals 6,000 years ago or that everyone on Earth is descended from Noah's family, but the scattering of the tribes of Israel is a historical event with names, dates and places and I feel that anthropologists simply dissociate themselves from any such ideas because they don't want to appear to be religious zealots to their colleagues because it may ruin their career.

I'm simply making the observation that there was a large shift in genes of the European people sometime in the last 4-5k years, and no one asks what signal if any the lost tribes could have played in that genetic transition.

Hunter-gatherers from remote northern Spain comprised of more than a single component 7000+ years ago. You're trying to tell us that a population from 2000-1500BC was a single component adjacent to the heart of civilization - a region to have many disparate people becoming intertwined. Your comment parallels someone suggesting "North European" found in Britain is the result of viking invasions. Seriously.

Sorry, I never responded to your post earlier about the single component.

No, I do not think that the Israelites were 100% of any single component, I completely agree with you. I do however suggest that they had a large portion of the Caucasus component and that they are a possible source for its recent arrival into Europe.

For us Believers in the ALmighty Creator, we also believe that the Genesis, although giving a general description of the descendants of Noah, gives an authritative valid explanation, even better than any speculation or present-day-based genetic studies. Why? You cannot explain the linguistic difference of the Basque people; but you gave a hint: this people is not much different than the surrounding people. Genesis gives us an account of the peoples that were formed and spreaded from that region Levante-Anatolia-Caucasus as you rightly pointed out, so there is no discrepancy here. Furthermore, the Bible explains us that God Almighty confounded the languages of these people; that was a major reason for their spreading all around the world. SO there you have it, the explanation of why the Basques have a language that resembles to none other, because they arrived first, directly, much earlier than others since Babel Time. They were cousins of the others as the Bible explains; this also explains both genetic differences and similarities with other people. However, I don't expect that people wh have not the fear of God Almighty, Jehova, will accept His Word. Therefore, they remain in their sins, and in darkness, because they cannot see the Light nor the Truth, which could save them, in Jesus Christ, our God and saviour.

I've just found the blog, 5 or 6 hours ago and i've been reading the articles and most of the comments with a lot of interest, although i'm a newbie to all this. But this fellow right here, Max, just blew my mind. You've just thrashed science, threw it to the garbage without even blinking, man! You brought The J to the table, with all the arsenal: the word, the light, the truth. You cannot do that man! That's rude!...you've just ruined my day.

The Indo-European language is Anatolian. That's becoming more and more obvious to me. I know my Minoan ancestors were never conquered by Aryans sweeping in from the Steppes, and most linguists agree we spoke one. *I* think it was Italic.

I thought we might have been conquered by the Greeks back in 1450 BC. Turns out... not so much. The first organized state to do that is the Romans. Which would be fitting if they're descended from conservative Cretan colonists who'd resisted the "Greekification" of the culture.

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